Key changes:
- Added implementation for linux Application ::PrintCallStack ::CaptureCallStack and ::DumpCallStack .
- Added atomic_fixed_buffer and test for it.
- Added GPI_SURFACE_DESTROYED event to signal complete surface destroying.
- GPI_Surface on android now correctly resets its resources on context loss and sends GPI_SURFACE_RESET.
- Mutex refactored to remove uneeded class.
- Refactored ThreadStorage.
- Added spin_lock.
- Fixed not thread-safe window creation under windows[Issue:22].
- Fixed incorrect Folder::OpenFilePath behavior.
- Fixed reference counting in IPI devices.
- IPI_Gamepad for windows implementation (simple winmm).
